Security

LiteSpeed Web Server is designed with security as a top consideration.
LSWS supports SSL, has access control at server and virtual host levels,
and context-specific realm protection. Besides these standard features,
LSWS also has the following special security features:

Connection level limits:

IP-level throttling limits network bandwidth to and from a single IP
address regardless of the number of connections.

IP-level connection accounting limits the number of concurrent connections
from a single IP address. You can controll this with the connection
soft limit, connection hard limit, grace
period, and banned period settings in the WebAdmin console.

Request checking:

Every HTTP request is vetted by LiteSpeed Web Server. "/." is not allowed in
a decoded URL, thus denying accessing hidden files and parent directories.

Static file checking:

LiteSpeed Web Server will serve a static file only if the following conditions
are satisfied:

The file is readable by everyone.

The file is not executable.

The file is not in the access denied directory list.

The file does not contain symbolic link if symbolic links are not allowed.

By default, LiteSpeed Web Server does not index a directory by listing its
files, it has to be enabled explicitly.

External application firewall:

LiteSpeed Web Server forwards requests to external applications to process/generate
dynamic content. Those applications can use a lot of system resources. The performance of the
whole system will be severely degraded when system resource consumption reaches a certain point
-- when swapping space has to be used, for example. One way to conduct a DoS attack is to flood
the web server with concurrent requests to a cumbersome external application.

LiteSpeed Web Server can pipeline requests and control the concurrent level of external
application use to prevent overconsumption of system resources. LSWS caches requests and only
forwards completed requests to the external application. This means the external application
will not be held waiting while the server is receiving the request. LSWS also caches the
external application's response so that the external application can be released as soon as
the response is completed and does not have to wait for the client to receive the complete response.
This way the server can utilize fewer external application instances to serve more concurrent
requests and achieve higher performance and scalability. LiteSpeed Web Server also uses its
own virtual memory to cache the request and response body to minimize the usage of system
memory without sacrificing performance.

CGI resources consumption limit:

LiteSpeed Web Server restricts the amount of system resources that can be consumed by
CGI applications. For each request to a CGI script, the web server needs to
start a standalone CGI process to handle it. On a Unix system, the number of concurrent
processes is limited. With the CGI resources consumption limit, you can configure
the maximum number of concurrent CGI instances that the web server can launch.
Excessive concurrent processes will degrade the performance
of the whole system. (CGI processes are a common weapon for DoS attacks.)
A system process limit can be specified per user in order to control the number
of processes that can be spawned by a CGI application. Each process is further confined by CPU and memory limits.

Enhanced CGI/FastCGI security with suEXEC:

In order to reduce the security risks of a CGI or Fast CGI script, LiteSpeed Web Server can restrict the system resources the CGI script can access by running it in "suEXEC" mode.
"suEXEC" starts the CGI or Fast CGI script with a different user ID from that of the web server. This greatly improves security in
shared hosting environment by preventing one user's CGI script from accessing other users' files.